What happens if a Two-Headed Giant player has an effect that makes them lose poison counters?

In the Two-Headed Giant format, teams consist of two players who share a life total and a few rules interactions, including how various counters, like poison counters, are applied. A player losing poison counters affects the entire team, meaning that if one player has an effect that causes them to lose a certain number of poison counters, then both players on that team will have to lose the same amount of poison counters collectively.

This is grounded in the rule that poison counters are tracked collectively for the team. Because of that, when one player experiences an effect that impacts poison counters, it is applied uniformly to the team, making it crucial for players in the Two-Headed Giant format to communicate and manage their collective counters effectively.

The other options do not align with how poison counters work in this format: only one player losing counters does not represent the shared nature of counters in Two-Headed Giant; claiming that players do not lose poison counters at all contradicts the game's mechanics; and the idea of a required sacrifice doesn’t relate to the poison counter interactions within this format. Thus, the correct interpretation is that both players on the team lose poison counters equally when affected by such an effect.